1. Technical Field
Exemplary embodiments relate to an electronic device, and more particularly, to a non-volatile memory device and a memory system that implements the non-volatile memory device.
2. Discussion of the Related Art
Semiconductor memory devices are a vital microelectronic component commonly found in digital logic systems, such as computers, and microprocessor-based applications ranging from satellites to consumer electronics. Therefore, advances in the fabrication of semiconductor memory devices, including process enhancements and circuit-design-related developments that allow scaling to higher memory densities and faster operating speeds, help establish performance standards for other digital logic families.
Semiconductor memory devices are divided into volatile semiconductor memory devices and non-volatile semiconductor memory devices. A non-volatile semiconductor memory device can retain stored data even at power-off. Data stored in the non-volatile semiconductor memory device is permanent or reprogrammable according to the memory fabrication technology. The non-volatile semiconductor memory device has been used to store data and program codes in systems such as computers and microprocessor-based applications ranging from satellites to consumer electronics.
A representative example of the non-volatile semiconductor memory device is a flash memory device. As high-density memory devices are needed more and more, multi-bit memory devices which store multi-bit data in one memory cell are typically used. However, such multi-bit memory devices can result in the possibility of more errors since storing multi-bit data in one memory cell reduces the voltage margin separating voltage levels (states) in the cell that yield the desired bit information.